Anomaly detection system for detecting anomaly in multiple control systems

ABSTRACT

An anomaly detection system for detecting an anomaly in a plurality of control systems comprises a plurality of analysis devices that are associated with the respective control systems and that acquire an event occurring in an associated control system and analyze the event to determine whether there is an anomaly. A first analysis device among the plurality of analysis devices determines whether an event occurring in the associated control system is to be indicated to a second analysis device among the plurality of analysis devices, and the second analysis device determines that there is an anomaly on condition that the event indicated by the first analysis device has correlation with an event indicated by an analysis device other than the first analysis device.

TECHNICAL FIELD

The present invention relates to an anomaly detection system fordetecting an anomaly in multiple control systems.

BACKGROUND ART

Industrial control systems (ICS) are known that manage and controlindustrial and infrastructure systems (see Non-Patent Literature 1, forexample). Many of conventional industrial control systems are notconnected with an external network and operate with specific protocols.Recent industrial control systems, however, are increasingly connectedwith an external network through a generic protocol, such as theInternet protocol. This enables multiple industrial control systems tocooperate with each other.

-   [Patent Literature 1] National Publication of International Patent    Application No. 2007-506353-   [Non-Patent Literature 1] “SCADA”, (online), Wikipedia, (searched on    Mar. 30, 2011), the Internet, URL:    http://ja.wikipedia.org/wiki/SCADA

SUMMARY OF INVENTION Problem to be Solved by the Invention

Industrial control systems continuously monitor their internal devicesor the like for anomalies; however, multiple industrial control systemshave not been cooperatively monitoring an anomaly.

Means for Solving the Problem

To solve the problem, a first aspect of the invention provides ananomaly detection system for detecting an anomaly in a plurality ofcontrol systems, the anomaly detection system comprising a plurality ofanalysis devices that are associated with the respective control systemsand that acquire an event occurring in an associated control system andanalyze the event to determine whether there is an anomaly, wherein afirst analysis device among the plurality of analysis devices determineswhether an event occurring in the associated control system is to beindicated to a second analysis device among the plurality of analysisdevices; and the second analysis device determines that there is ananomaly on condition that the event indicated by the first analysisdevice has correlation with an event indicated by an analysis deviceother than the first analysis device. A method and a program for thesystem are also provided.

The summary of the invention does not list all of the essential featuresof the invention. A subcombination of such features may also be withinan invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a configuration of a computing system 10 according to anembodiment of the invention;

FIG. 2 shows a configuration of a first analysis device 30-1 and asecond analysis device 30-2 according to the embodiment;

FIG. 3 shows a process flow of the first analysis device 30-1 and secondanalysis device 30-2 according to the embodiment;

FIG. 4 shows an example of events acquired by the first analysis device30-1 and an example of events sent by the first analysis device 30-1;

FIG. 5 shows an example of a table used for concealing additionalinformation; and

FIG. 6 shows an exemplary hardware configuration of a computer 1900according to the embodiment.

MODE FOR CARRYING OUT THE INVENTION

While the present invention is described below with reference to itsembodiment, the embodiment is not intended to limit the claimedinvention. Also, not all combinations of the features set forth in theembodiment are essential for the solution of the invention.

FIG. 1 shows a configuration of a computing system 10 according to anembodiment. The computing system 10 of the embodiment includes multiplecontrol systems 20, multiple analysis devices 30, and a network 40.

Each of the control systems 20 is a system constituted by multipleinterconnected computers and devices. The control systems 20 each may bean industrial control system (ICS) for managing and controlling objectsof an industry or infrastructure (e.g., traffic, energy) system, forexample. In this case, the control systems 20 have multiple devices, aprogrammable logic controller (PLC) to control the devices, a server andthe like.

The control systems 20 may each be a system to manage various devicesconnected to a network within a building (e.g., a system forelectricity, gas, water, air conditioning, or security), for example.Each of the control systems 20 may also be a partial system of a largecontrol system. For example, the control systems 20 may each be apartial management system constituting a system that is responsible formanaging a whole city (e.g., a system for managing buildings, plants,water supply, electricity, etc.).

The control systems 20 may also be systems for managing various devices(e.g., telephones, copiers) connected with an office or house network,for example. The control systems 20 may also be systems for managingcomputers connected with a network within a corporation or the like, orsystems for managing a large number of servers connected with a networkof a data center or the like.

The analysis devices 30 are respectively associated with the controlsystems 20. Each of analysis devices 30 may be associated with one, ortwo or more control systems 20. The analysis devices 30 each acquireevents that occur in the associated control system(s) 20 and analyze theevents to determine whether there is an anomaly in the control system(s)20.

An event refers to an incident that occurs in an associated one of thecontrol systems 20 and that can be detected by a sensor or a computer,for example. For example, an event may be a physical amount (such aselectricity, temperature, humidity, mass, volume, and flow rate)detected by a sensor provided for a device or the like within thecontrol system 20. An event may also be a measurement of data that isinput and output to and from an information processor or the like withinthe control system 20 (e.g., data rate, response to data transmissionand reception, and error rate), for example. An event may also be thestate of a device in the control system 20 (e.g.,operating/non-operating, and operation mode), or the state of resourcesconstituting the information processor in the control system 20 (e.g.,memory usage, processor utilization).

Each of the analysis devices 30 acquires events occurring in theassociated control system 20 and determines whether a predefined eventis acquired. When a predefined event is acquired, each of the analysisdevices 30 determines that there is an anomaly in the associated controlsystem 20. Upon determining that the associated control system 20 has ananomaly, the analysis device 30 carries out processing for handling theanomaly.

The network 40 connects between the control systems 20 and analysisdevices 30 to enable data transmission and reception therebetween. Thenetwork 40 transmits data according to a generic protocol, e.g., theInternet protocol.

FIG. 2 shows a configuration of a first analysis device 30-1 and asecond analysis device 30-2 according to the present embodiment. Theanalysis devices 30 in the computing system 10 according to the presentembodiment cooperate with each other to function as an anomaly detectionsystem for detecting anomalies in the control systems 20.

More specifically, the first analysis device 30-1 among the analysisdevices 30 indicates an event acquired from the associated controlsystem 20 to the second analysis device 30-2 among the analysis devices30. The second analysis device 30-2 then determines whether there iscorrelation between the event from the first analysis device 30-1 andone from an analysis device 30 other than the first analysis device30-1, and determines that there is an anomaly if they have correlation.

In the present embodiment, at least one of the analysis devices 30included in the computing system 10 serves as the second analysis device30-2. The other analysis devices 30 than the second analysis device 30-2function as the first analysis devices 30-1.

The first analysis device 30-1 includes at least an analysis unit 50that acquires events occurring in the associated control system 20 andanalyzes the events to determine whether the control system has ananomaly. The second analysis device 30-2 includes at least an analysiscontrol unit 70 that determines whether there is an anomaly in any ofthe control systems 20. The second analysis device 30-2 may furtherinclude the analysis unit 50.

The analysis unit 50 includes an acquisition unit 52, a determinationunit 54, a standardization unit 56, a concealment unit 58, an eventsending unit 60, an anomaly receiving unit 62, and a monitoring unit 64.The analysis control unit 70 includes an event receiving unit 72, acorrelation detecting unit 74, and an anomaly sending unit 76.

The acquisition unit 52 acquires events occurring in the associatedcontrol system 20. For example, the acquisition unit 52 acquiresphysical amounts (such as electricity, temperature, humidity, mass,volume, and flow rate) detected by physical sensors located at certainpoints within the control systems 20 as events. The acquisition unit 52may also acquire measurements of data that is input and output to andfrom an information processor or the like within the control system 20(e.g., data rate, response to data transmission and reception, and errorrate) as events, for example. The acquisition unit 52 may also acquirethe state of devices within the control system 20 or the state ofresources constituting the information processor in the control system20 (e.g., usage of memory, processor utilization) as events.

The determination unit 54 determines whether the associated controlsystem 20 has an anomaly or not based on an acquired event. For example,the determination unit 54 determines whether an acquired event has apredetermined value.

For example, the determination unit 54 determines that the associatedcontrol system 20 has an anomaly when a physical amount detected by asensor falls outside a predetermined normal range. The determinationunit 54 may also determine that the associated control system 20 has ananomaly if a measurement of data input and output to and from aninformation processor in the control system 20 falls outside apredetermined normal range, for example. The determination unit 54 mayalso determine that the associated control system 20 has an anomaly if adevice in the control system 20 or a resource constituting theinformation processor in the control system 20 is in a predeterminedstate, for example.

When the determination unit 54 determines that the associated controlsystem 20 has an anomaly, it notifies the monitoring unit 64 of theanomaly. Upon being notified of the anomaly by the determination unit54, the monitoring unit 64 performs a handling process that should bedone when there is an anomaly. For example, the monitoring unit 64reports the anomaly to an administrator of the associated control system20. The monitoring unit 64 may also increase the frequency of monitoringthe associated control system 20, for example. In this case, themonitoring unit 64 increases the frequency of event acquisition at theacquisition unit 52, for example. The monitoring unit 64 may alsodeactivate the anomalous device or shut off power supply to it.

The determination unit 54 further determines whether or not to indicateevents occurring in the associated control system 20 to the secondanalysis device 30-2 even if the associated control system 20 isdetermined not to be anomalous. In the present embodiment, thedetermination unit 54 determines that an event acquired should beindicated to the second analysis device 30-2 if the event has a valuethat is not determined as anomalous and if the difference between thevalue and a threshold of anomaly determination is within a predeterminedrange. The determination unit 54 may also determine that an event withwhich the associated control system 20 is determined as anomalous shouldalso be indicated to the second analysis device 30-2.

As an example, the determination unit 54 determines that an event shouldbe indicated to the second analysis device 30-2 if a physical amountdetected by a sensor or a measurement of data that is input and outputto and from an information processor in the control system 20 fallswithin a predetermined normal range (a range in which the associatedsystem is determined to be normal) and if the difference between thevalue and a threshold of anomaly determination is within a predeterminedrange. As another example, the determination unit 54 determines that anevent should be indicated to the second analysis device 30-2 if a devicein the control system 20 or a resource constituting the informationprocessor in the control system 20 is in a state with which the controlsystem 20 is determined to be normal and also in a predefined state.

The standardization unit 56 standardizes the data format for an eventthat occurred in the associated control system 20 and has beendetermined to be indicated to the second analysis device 30-2 at thedetermination unit 54. More specifically, the standardization unit 56standardizes an event that has been determined to be indicated to thesecond analysis device 30-2 by converting the data format of the eventinto a data format for the second analysis device 30-2. Thestandardization unit 56 may also convert the data format of an eventthat occurred in the associated control system 20 into a standard dataformat for the multiple control systems 20 to standardize the event, forexample. The standardization unit 56 can thereby convert an event to beindicated to the second analysis device 30-2 into a data format that isreadable by the second analysis device 30-2.

The concealment unit 58 conceals part of data describing an eventoccurring in the associated control system 20 that has been determinedby the determination unit 54 to be indicated to the second analysisdevice 30-2. By way of example, the concealment unit 58 conceals aportion of data describing an event that should not be revealed to otheranalysis devices 30. For example, the concealment unit 58 conceals datathat represents a matter that should not be revealed to theadministrators of the other control systems 20 for ensuring security(e.g., the installation location and performance of a sensor).

The event sending unit 60 sends an event in the associated controlsystem 20 that has been standardized by the standardization unit 56 anda part of data of which has been concealed by the concealment unit 58 tothe analysis control unit 70 of the second analysis device 30-2. Theanalysis unit 50 of the first analysis device 30-1 converts the eventinto a message and sends it to the analysis control unit 70 of thesecond analysis device 30-2 over the network 40. The analysis unit 50 ofthe second analysis device 30-2 may indicate an event to the analysiscontrol unit 70 via or without via the network 40.

The event receiving unit 72 of the analysis control unit 70 receivesevents sent from the analysis devices 30. More specifically, the eventreceiving unit 72 receives events sent from the analysis unit 50 of thefirst analysis device 30-1 and events sent from the analysis unit 50 ofthe second analysis device 30-2.

The correlation detecting unit 74 of the analysis control unit 70compares events sent from the analysis devices 30 with each other todetermine whether the events have a correlation equal to or greater thana predetermined correlation value. The correlation detecting unit 74determines that one of analysis devices 30 is anomalous if events sentfrom the analysis devices 30 have a correlation equal to a predeterminedcorrelation value or greater, for example.

The anomaly sending unit 76 of the analysis control unit 70 indicates ananomaly to the analysis unit 50 of respective first analysis devices30-1 and the analysis unit 50 of the second analysis device 30-2 if thecorrelation detecting unit 74 determines that there is an anomaly. Inthis case, the anomaly sending unit 76 provides, in anomaly information,data on a concealed portion included in an event that was sent from ananalysis device 30 and that has been determined to have a correlationwith an event sent from another analysis device 30 and be anomalous tothe analysis unit 50 of the analysis devices 30.

The anomaly receiving unit 62 receives the anomaly information sent bythe analysis control unit 70 of the second analysis device 30-2. Theanomaly receiving unit 62 transfers the anomaly information to theconcealment unit 58.

The concealment unit 58 clears the concealment of the concealed dataportion included in the anomaly information. The concealment unit 58transfers the anomaly information and the unconcealed data to themonitoring unit 64.

In response to indication of anomaly information from the analysiscontrol unit 70 of the second analysis device 30-2, the monitoring unit64 identifies the specifics of the anomaly indicated from the secondanalysis device 30-2. For example, when the concealment unit 58indicates an event with the installation location of a sensor concealed,the monitoring unit 64 detects the installation location of the sensorfrom the unconcealed data. This allows the concealment unit 58 to locatethe sensor that caused an event that has been determined by the secondanalysis device 30-2 to be anomalous. The monitoring unit 64 thencarries out a handling process that should be done in the event of ananomaly.

FIG. 3 shows a process flow between the first analysis device 30-1 andthe second analysis device 30-2 according to the present embodiment.FIG. 4 shows an example of events acquired by the first analysis device30-1 and an example of events sent by the first analysis device 30-1.FIG. 5 shows an example of a table used for concealing additionalinformation.

First at step S11, the first analysis device 30-1 acquires events thatoccur in the associated control system 20 at certain time intervals. Inthe example of FIG. 4, the first analysis device 30-1 acquires thetemperature of a device installed in the backyard of a building managedby the associated control system 20 as events every ten minutes.

Then at step S12, the first analysis device 30-1 determines whether ornot to indicate each one of the events it regularly acquired to thesecond analysis device 30-2. As an example, the first analysis device30-1 determines that the event should be indicated to the secondanalysis device 30-2 when a change in the event is greater than apredetermined amount of change.

In the example of FIG. 4, the first analysis device 30-1 determines thata temperature (an event) should be indicated to the second analysisdevice 30-2 if the temperature (an event) of the device in the backyardof the building managed by the associated control system 20 has changedby a predetermined amount or more in the last ten minutes. If the firstanalysis device 30-1 determines to indicate the event (S12: YES), thefirst analysis device 30-1 proceeds to step S13.

At step S13, the first analysis device 30-1 standardizes the data formatof the event in question. By way of example, the first analysis device30-1 converts identification information describing the event and anevent value indicating the value of the event to a data format that isreadable by the second analysis device 30-2 (e.g., a data format commonin the computing system 10).

In the example of FIG. 4, the first analysis device 30-1 convertsindividual identification information represented as “temperature” tocommon identification information represented as “temperature sensor”.Also in the example of FIG. 4, the first analysis device 30-1 converts“time” represented in 12-hour format (an individual event value) into“time” represented in 24-hour format (a common event value). In theexample of FIG. 4, the first analysis device 30-1 also converts“temperature” represented in Fahrenheit (an individual event value) into“temperature” represented in Celsius (a common event value).

Then at step S14, the first analysis device 30-1 conceals a portion ofdata describing the event to be indicated that should not be revealed toother analysis devices 30 (e.g., data relating to security, data showingspecific locations of event measurement). As an example, the firstanalysis device 30-1 conceals sensor position information, which isadditional information on the event. In the example of FIG. 4, the firstanalysis device 30-1 conceals sensor position information represented as“backyard #1” into a random code “39485”.

The first analysis device 30-1 also stores a conversion table showingthe correspondence between unconcealed data and concealed data, forexample, and conceals data with reference to the conversion table. Inthis example, the first analysis device 30-1 stores a conversion tablefor converting sensor position information representing sensor positions(backyard #1, backyard #2, main door #1, main door #2) intocorresponding random codes (39485, 13456, 27321, 53884), such as the oneshown in FIG. 5, for example.

At step S15, the first analysis device 30-1 selects at least one secondanalysis device 30-2 from the analysis devices 30 as the destination ofevent transmission. For example, when there are two or more analysisdevices 30 that are able to receive events from multiple analysisdevices 30 and determine whether an anomaly occurred, the first analysisdevice 30-1 selects one, or two or more analysis devices 30 as thesecond analysis device(s) 30-2 from those devices.

The first analysis device 30-1 may dynamically change the deviceselected for the second analysis device 30-2 from the analysis devices30. For example, the first analysis device 30-1 designates the secondanalysis device 30-2 for each certain time period (e.g., a day, a week).

In this case, the first analysis device 30-1 may give a higher priorityto an analysis device 30 with a short response time when selecting thesecond analysis device 30-2 from the analysis devices 30. This enablesthe first analysis device 30-1 to receive an indication of an anomalyfaster. The first analysis device 30-1 may also select a new secondanalysis device 30-2 after event indication to the same second analysisdevice 30-2 has continued for a certain period or longer. The firstanalysis device 30-1 thereby can prevent one analysis device fromfixedly being the second analysis device 30-2.

Then at step S16, the event that has been standardized at step S13 andconcealed at step S14 is indicated to the second analysis device 30-2selected at step S15. At step S17, the second analysis device 30-2receives the event from the first analysis device 30-1.

At step S18, the second analysis device 30-2 detects correlation betweenevents indicated from multiple analysis devices 30 and determineswhether any of the control systems has an anomaly. More specifically,the second analysis device 30-2 determines that there is an anomaly ifan event indicated from the first analysis device 30-1 has correlationwith an event indicated from an analysis device 30 other than the firstanalysis device 30-1. By way of example, the second analysis device 30-2determines that there is an anomaly if there is a correlation equal toor greater than a predetermined correlation value between a change inevents indicated by the first analysis device 30-1 and a change inevents indicated by an analysis device 30 other than the first analysisdevice 30-1.

For example, the correlation detecting unit 74 determines that there isan anomaly if temperatures from multiple temperature sensorsrespectively provided in control systems 20 have changed with a mutualcorrelation. In the example of FIG. 4, changes occur in a control system20 including the temperature detected by a temperature sensor increasingbetween 20:20 and 20:30 and the temperature detected by the temperaturesensor dropping between 20:30 and 20:40. In such a case, the secondanalysis device 30-2 determines an anomaly if a temperature sensorprovided in the control systems 20 show a change in temperature similarto those shown in FIG. 4.

If the second analysis device 30-2 determines there is an anomaly atstep S18, the second analysis device 30-2 then indicates the anomaly tothe first analysis device 30-1 at step S19. In this case, the secondanalysis device 30-2 provides, in anomaly information, the analysis unit50 with data on the concealed portion included in the event that wassent from the first analysis device 30-1 and that has been determined tobe correlated with an event sent from another analysis device 30 and beanomalous.

Then at step S20, the first analysis device 30-1 receives the anomalyinformation sent from the second analysis device 30-2. At step S21, thefirst analysis device 30-1 identifies the specifics of the anomaly ofthe associated control system 20 from the anomaly information sent fromthe second analysis device 30-2.

The first analysis device 30-1 puts the concealed data portion in theanomaly information from the second analysis device 30-2 back intounconcealed data with reference to the conversion table. The firstanalysis device 30-1 then identifies the anomaly that occurred in theassociated control system from the now unconcealed event. For example,the first analysis device 30-1 finds out that the anomaly occurred inthe sensor in the backyard of the building with reference to such aconversion table as shown in FIG. 5.

At step S22, the first analysis device 30-1 changes a mode forcontrolling the associated control system 20 to an alert mode. The firstanalysis device 30-1 reports the anomaly to the administrator of theassociated control system 20. The first analysis device 30-1 alsoincreases the frequency of monitoring the associated control system 20,e.g., by increasing the frequency of event acquisition. The firstanalysis device 30-1 may also deactivate the anomalous device and/orshut off the power supply to it.

As described above, with the computing system 10 according to thepresent embodiment, an anomaly can be detected from occurrence ofincidents or events having certain correlation with each other onmultiple analysis devices 30 even if each one of the incidents or eventsis not detected as an anomaly in itself in a single control system 20.The computing system 10 therefore permits multiple analysis devices 30to cooperate to detect an anomaly with higher accuracy and sensitivity.

The second analysis device 30-2 may request an unconcealed event fromthe first analysis device 30-1 when an event indicated from the firstanalysis device 30-1 has correlation with an event indicated from ananalysis device 30 other than the first analysis device 30-1. In thiscase, the first analysis device 30-1 indicates an event withoutconcealment to the second analysis device 30-2 in response to therequest for an unconcealed event.

The second analysis device 30-2 then receives the unconcealed event fromthe first analysis device 30-1 and again determines whether there iscorrelation between the unconcealed event from the first analysis device30-1 and the event from the analysis device 30 other than the firstanalysis device 30-1. If the events have correlation, the secondanalysis device 30-2 determines that there is an anomaly. The secondanalysis device 30-2 thus can determine occurrence of an anomaly moreaccurately.

FIG. 6 shows an exemplary hardware configuration of a computer 1900according to the present embodiment. The computer 1900 according to thepresent embodiment includes a CPU peripheral portion having a CPU 2000,a RAM 2020, a graphics controller 2075, and a display device 2080, whichare interconnected by a host controller 2082, an input/output portionhaving a communication interface 2030, a hard disk drive 2040, and aCD-ROM drive 2060, which are connected with the host controller 2082through an input/output controller 2084, and a legacy input/outputportion having a ROM 2010, a flexible disk drive 2050, and aninput/output chip 2070, which are connected with the input/outputcontroller 2084.

The host controller 2082 connects the RAM 2020 with the CPU 2000 and thegraphics controller 2075, which access the RAM 2020 at a high transferrate. The CPU 2000 operates according to programs stored in the ROM 2010and RAM 2020 to control components. The graphics controller 2075acquires image data generated by the CPU 2000 or the like in a framebuffer provided in the RAM 2020 and has it displayed on the displaydevice 2080. Alternatively, the graphics controller 2075 may internallyinclude a frame buffer for storing image data generated by the CPU 2000or the like.

The input/output controller 2084 connects the host controller 2082 withthe communication interface 2030, hard disk drive 2040, and CD-ROM drive2060, which are relatively fast input/output devices. The communicationinterface 2030 communicates with other devices over a network. The harddisk drive 2040 stores programs and data that are used by the CPU 2000of the computer 1900. The CD-ROM drive 2060 reads a program or data fromthe CD-ROM 2095 and supplies it to the hard disk drive 2040 via the RAM2020.

The input/output controller 2084 is connected with the ROM 2010, andalso with the flexible disk drive 2050 and the input/output chip 2070,which are relatively slow input/output devices. The ROM 2010 stores aboot program executed at start-up by the computer 1900 and/or programsthat are dependent on the hardware of the computer 1900. The flexibledisk drive 2050 reads a program or data from the flexible disk 2090 andsupplies it to the hard disk drive 2040 via the RAM 2020. Theinput/output chip 2070 connects the flexible disk drive 2050 with theinput/output controller 2084 and also connects various input/outputdevices with the input/output controller 2084 by way of a parallel port,serial port, keyboard port, or mouse port, for example.

Programs that are provided to the hard disk drive 2040 through the RAM2020 are supplied by the user being stored in a recording medium such asthe flexible disk 2090, CD-ROM 2095, or an IC card. The programs areread from the recording medium and installed in the hard disk drive 2040in the computer 1900 via the RAM 2020 and executed at the CPU 2000.

Programs that are installed on the computer 1900 and cause the computer1900 to function as the analysis unit 50 include an acquisition module,a determination module, a standardization module, a concealment module,an event sending module, an anomaly receiving module, and a monitoringmodule. These programs or modules operate on the CPU 2000 and the liketo cause the computer 1900 to function as the acquisition unit 52,determination unit 54, standardization unit 56, concealment unit 58,event sending unit 60, anomaly receiving unit 62, and monitoring unit64.

Information processing described in the programs is read into thecomputer 1900 to function as the acquisition unit 52, determination unit54, standardization unit 56, concealment unit 58, event sending unit 60,anomaly receiving unit 62, and monitoring unit 64, which are specificmeans realized through cooperation of software and the various hardwareresources described above. These specific means then implement operationor modification of information according to an application of thecomputing system 10 in the present embodiment so that the analysis unit50 specific to the application is built.

Programs that are installed on the computer 1900 and cause the computer1900 to function as the analysis control unit 70 include an eventreceiving module, a correlation detecting module, and an anomaly sendingmodule. These programs or modules operate on the CPU 2000 and the liketo cause the computer 1900 to function as the event receiving unit 72,correlation detecting unit 74 and anomaly sending unit 76.

Information processing described in the programs is read into thecomputer 1900 to function as the event receiving unit 72, correlationdetecting unit 74 and anomaly sending unit 76, which are specific meansrealized through cooperation of software and the various hardwareresources described above. These specific means then implement operationor modification of information according to the application of thecomputing system 10 in the present embodiment so that the analysiscontrol unit 70 specific to the application is built.

By way of example, when communication is performed between the computer1900 and an external device or the like, the CPU 2000 executes acommunication program loaded in the RAM 2020, and instructs thecommunication interface 2030 on communication processing in accordancewith processing described in the communication program. Thecommunication interface 2030 reads data for transmission stored in asend buffer area provided in a storage device, such as the RAM 2020,hard disk drive 2040, flexible disk 2090, or CD-ROM 2095, and sends thedata to a network under control of the CPU 2000, or writes data receivedfrom the network in a receive buffer area provided in the storagedevice. Thus, the communication interface 2030 may transfertransmission/received data to the storage device by direct memory access(DMA), or alternatively, the CPU 2000 may read data from a sourcestorage or the communication interface 2030 and writes the data into adestination communication interface 2030 or storage device, therebytransferring transmission/received data.

The CPU 2000 also reads all or only required data from a file or adatabase stored in an external storage device, such as the hard diskdrive 2040, CD-ROM drive 2060 (CD-ROM 2095), flexible disk drive 2050(flexible disk 2090), into the RAM 2020 by DMA transfer or the like andperforms various processing on the data in the RAM 2020. The CPU 2000then writes processed data back into the external storage device by DMAtransfer or the like. Because the RAM 2020 can be considered totemporarily hold the contents of the external storage device during sucha process, the present embodiment generically refers to the RAM 2020 andthe external storage device or the like as memory, storage, or a storagedevice. Various programs and information such as data, tables, anddatabases in the present embodiment are stored in the storage device andsubjected to information processing. The CPU 2000 may also hold part ofdata from the RAM 2020 in cache memory and perform data read and writein the cache memory. Because cache memory is responsible for some offunctions of the RAM 2020 also in such an arrangement, the presentembodiment assumes that cache memory is also included in the RAM 2020,memory, and/or a storage device unless it is specificallydifferentiated.

The CPU 2000 also performs various kinds of processing, including thevarious arithmetic operations, modification to information, conditionaldetermination, information retrieval, and replacement described in theembodiment, which are specified by instruction lines in programs, ondata read from the RAM 2020 and writes back the data into the RAM 2020.For example, when performing conditional determination, the CPU 2000determines whether any of variables shown in the embodiment satisfies acertain condition, such as being greater, smaller, equal to or greaterthan, equal to or smaller than, or equal to another variable or aconstant, and branches to a different instruction line or calls asub-routine if the condition holds (or does not hold).

The CPU 2000 also can search for information stored in a file ordatabase within a storage device. For example, when a number of entriesare stored in a storage device and in each of the entries the attributevalue of a first attribute is associated with the attribute value of asecond attribute, the CPU 2000 searches for an entry with the attributevalue of the first attribute matching a specified condition from theentries in the storage device, and reads the attribute value of thesecond attribute stored in that entry, thereby obtaining the attributevalue of the second attribute associated with the first attribute thatsatisfies the condition.

The programs or modules may be stored in an external recording medium,which may be the flexible disk 2090, CD-ROM 2095, or an opticalrecording medium such as a DVD and CD, a magneto-optical recordingmedium such as an MO, a tape medium, or semiconductor memory such as anIC card. Alternatively, a storage device, such as a hard disk or RAM,provided in a server system connected to a dedicated communicationnetwork or the Internet may be used as the recording medium, and theprograms can be provided to the computer 1900 over the network.

While the present invention has been described with reference to itsembodiment, the technical scope of the invention is not limited to thescope set forth in the embodiment. It will be apparent to those skilledin the art that various modifications or improvements may be made to theembodiment. It is apparent from descriptions in Claims that embodimentswith such modifications or improvements can be encompassed within thetechnical scope of the invention.

It should be noted that the order of executing processes, such asactions, procedures, steps, and phases in the devices, system, programs,and method set forth in the Claims, specification, and drawings may beperformed in any order unless specifically stated as “before”, “priorto”, or the like, and unless output from the preceding process is usedin the subsequent process. “First”, “then” or the like, even if used inrelation to a process flow in the Claims, specification, and drawingsfor convenience, do not mean that execution in the described order isessential.

DESCRIPTION OF SYMBOLS

-   10 computing system-   20 control system-   30 analysis device-   40 network-   50 analysis unit-   52 acquisition unit-   54 determination unit-   56 standardization unit-   58 concealment unit-   60 event sending unit-   62 anomaly receiving unit-   64 monitoring unit-   70 analysis control unit-   72 event receiving unit-   74 correlation detecting unit-   76 anomaly sending unit-   1900 computer-   2000 CPU-   2010 ROM-   2020 RAM-   2030 communication interface-   2040 hard disk drive-   2050 flexible disk drive-   2060 CD-ROM drive-   2070 input/output chip-   2075 graphics controller-   2080 display device-   2082 host controller-   2084 input/output controller-   2090 flexible disk-   2095 CD-ROM

The invention claimed is:
 1. An anomaly detection system for detectingan anomaly in a plurality of control systems, the anomaly detectionsystem comprising: a plurality of analysis devices that are associatedwith the respective control systems and that acquire an event occurringin an associated control system and analyze the event to determinewhether there is an anomaly, wherein; a first analysis device among theplurality of analysis devices determines whether an event occurring inthe associated control system is to be indicated to a second analysisdevice among the plurality of analysis devices; and the second analysisdevice determines that there is an anomaly on condition that the eventindicated by the first analysis device has correlation with an eventindicated by an analysis device other than the first analysis device. 2.The anomaly detection system according to claim 1, wherein each of theplurality of analysis devices comprises a standardization unit thatconverts a data format for an event occurring in the associated controlsystem into a data format for the second analysis device, therebystandardizing the event.
 3. The anomaly detection system according toclaim 2, wherein the standardization unit of the first analysis deviceconverts the data format for an event occurring in the associatedcontrol system into a standard data format for the plurality of controlsystems, thereby standardizing the event.
 4. The anomaly detectionsystem according to claim 1, wherein each of the plurality of analysisdevices comprises a concealment unit that conceals a portion of datadescribing an event occurring in the associated control system.
 5. Theanomaly detection system according to claim 4, wherein the concealmentunit of the first analysis device stores a conversion table that showscorrespondence between unconcealed data and concealed data, the secondanalysis device provides the first analysis device with anomalyinformation including concealed data included in a concealed eventreceived from the first analysis device when the second analysis devicedetermines that there is an anomaly; and the concealment unit of thefirst analysis device converts the concealed data included in theanomaly information provided by the second analysis device intounconcealed data with reference to the conversion table, and identifiesthe anomaly that occurred in the associated control system.
 6. Theanomaly detection system according to claim 4, wherein the secondanalysis device requests the first analysis device to indicate anunconcealed event if an event indicated by the first analysis device hascorrelation with an event indicated by an analysis device other than thefirst analysis device, receives an unconcealed event from the firstanalysis device, and determines that there is an anomaly on conditionthat the unconcealed event indicated by the first analysis device hascorrelation with the event indicated by the analysis device other thanthe first analysis device.
 7. The anomaly detection system according toclaim 1, wherein; the second analysis device indicates an anomaly to atleast some of the plurality of analysis devices, and at least one of theplurality of analysis devices to which the anomaly has been indicatedincrease a frequency of monitoring the associated control system.
 8. Theanomaly detection system according to claim 1, wherein the firstanalysis device dynamically changes an analysis device that is selectedas the second analysis device from among the plurality of analysisdevices.
 9. The anomaly detection system according to claim 8, whereinthe first analysis device selects a new second analysis device afterevent indication to a same second analysis device has continued for acertain period or longer.
 10. The anomaly detection system according toclaim 8, wherein the first analysis device gives a higher priority to ananalysis device with a short response time when selecting the secondanalysis device from the plurality of analysis devices.
 11. The anomalydetection system according to any one of claims 1, wherein; the firstanalysis device comprises an analysis unit that acquires eventsoccurring in the associated control system and analyzes the events todetermine whether the control system has an anomaly, the second analysisdevice comprises an analysis control unit that determines whether any ofthe plurality of control systems has an anomaly, the analysis unit ofthe first analysis device acquires an event occurring in the associatedcontrol system and determines whether or not to indicate the event tothe second analysis device, and transfers the event to the analysiscontrol unit of the second analysis device if the analysis unitdetermines that the event is to be indicated to the second analysisdevice, the analysis control unit of the second analysis device detectscorrelation between events from a plurality of first analysis devices,and determines that there is an anomaly on condition that the events hascorrelation, and indicates the anomaly to the analysis unit of the firstanalysis device if the analysis control unit determines that there is ananomaly, and the analysis unit of the first analysis device reports theanomaly indicated by the second analysis device to an administrator ofthe associated control system.
 12. The anomaly detection systemaccording to any one of claims 1, wherein; the second analysis deviceindicates an anomaly to the first analysis device if the second analysisdevice determines that there is an anomaly, and the first analysisdevice reports the anomaly indicated by the second analysis device tothe administrator of the control system.
 13. The anomaly detectionsystem according to any one of claims 1, wherein the second analysisdevice determines that there is an anomaly on condition that a change inevents indicated by the first analysis device has correlation with achange in events indicated by an analysis device other than the firstanalysis device.
 14. An anomaly detecting method for detecting ananomaly in a plurality of control systems, comprising: providing aplurality of analysis devices, wherein the plurality of analysis devicesare associated with the respective control systems and that acquire anevent occurring in an associated control system and analyze the event todetermine whether there is an anomaly, the method comprising:determining, by a first analysis device among the plurality of analysisdevices, whether an event occurring in the associated control system isto be indicated to a second analysis device among the plurality ofanalysis devices; and determining by the second analysis device thatthere is an anomaly on condition that the event indicated by the firstanalysis device has correlation with an event indicated by an analysisdevice other than the first analysis device.